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---
title: AnalyserNode.getByteTimeDomainData()
slug: Web/API/AnalyserNode/getByteTimeDomainData
translation_of: Web/API/AnalyserNode/getByteTimeDomainData
---
<p>{{ APIRef("Mountain View APIRef Project") }}</p>
<p>{{ domxref("AnalyserNode") }} 接口的 <strong><code>getByteTimeDomainData()</code></strong> 方法复制当前波形或时域数据到传递给它的 {{domxref("Uint8Array")}} (无符号字节数组) 中。</p>
<p>如果该数组的元素少于 {{domxref("AnalyserNode.fftSize")}}, 多余的元素会被丢弃。如果它有多于所需的元素，则忽略多余的元素。</p>
<h2 id="语法">语法</h2>
<pre class="brush: js">var audioCtx = new AudioContext();
var analyser = audioCtx.createAnalyser();
var dataArray = new Uint8Array(analyser.fftSize); // Uint8Array should be the same length as the fftSize
analyser.getByteTimeDomainData(dataArray); // fill the Uint8Array with data returned from getByteTimeDomainData()
</pre>
<h3 id="参数">参数</h3>
<dl>
<dt><code>array</code></dt>
<dd>时域数据将被复制到的 {{domxref("Uint8Array")}} 。<br>
如果数组中的元素少于 {{domxref("AnalyserNode.frequencyBinCount")}}, 则会删除多余的元素。如果它包含的元素多于需要的元素，则忽略多余的元素。</dd>
</dl>
<h3 id="返回值">返回值</h3>
<p><strong><code>void</code></strong> | None</p>
<h2 id="例子">例子</h2>
<p>以下的例子展示了 {{domxref("AudioContext")}} 生成一个 <code>AnalyserNode</code> 基础用法， 然后通过 {{domxref("window.requestAnimationFrame()","requestAnimationFrame")}} 和 {{htmlelement("canvas")}} 重复的收集和绘制一个当前音频输入的“示波器样式”输出。 有关更完整的应用实例/信息，请查看我们的 <a href="https://mdn.github.io/voice-change-o-matic/">Voice-change-O-matic</a> demo (有关代码请参阅 <a href="https://github.com/mdn/voice-change-o-matic/blob/gh-pages/scripts/app.js#L128-L205">app.js lines 128–205</a>)。</p>
<pre class="brush: js">var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var analyser = audioCtx.createAnalyser();
...
analyser.fftSize = 2048;
var bufferLength = analyser.frequencyBinCount;
var dataArray = new Uint8Array(bufferLength);
analyser.getByteTimeDomainData(dataArray);
// draw an oscilloscope of the current audio source
function draw() {
drawVisual = requestAnimationFrame(draw);
analyser.getByteTimeDomainData(dataArray);
canvasCtx.fillStyle = 'rgb(200, 200, 200)';
canvasCtx.fillRect(0, 0, WIDTH, HEIGHT);
canvasCtx.lineWidth = 2;
canvasCtx.strokeStyle = 'rgb(0, 0, 0)';
var sliceWidth = WIDTH * 1.0 / bufferLength;
var x = 0;
ctx.beginPath();
for(var i = 0; i < bufferLength; i++) {
let v = dataArray[i]/128.0,
y = v * HEIGHT/2;
if(i === 0)
canvasCtx.moveTo(x, y);
else
canvasCtx.lineTo(x, y);
x += sliceWidth;
}
canvasCtx.lineTo(canvas.width, canvas.height/2);
canvasCtx.stroke();
};
draw();
</pre>
<h2 id="规格">规格</h2>
<table class="standard-table">
<tbody>
<tr>
<th scope="col">Specification</th>
<th scope="col">Status</th>
<th scope="col">Comment</th>
</tr>
<tr>
<td>{{SpecName('Web Audio API', '#widl-AnalyserNode-getByteTimeDomainData-void-Uint8Array-array', 'getByteTimeDomainData()')}}</td>
<td>{{Spec2('Web Audio API')}}</td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="浏览器兼容性">浏览器兼容性</h2>
<div>
<p>{{Compat("api.AnalyserNode.getByteTimeDomainData")}}</p>
</div>
<h2 id="See_also">See also</h2>
<ul>
<li><a href="/en-US/docs/Web_Audio_API/Using_Web_Audio_API">Using the Web Audio API</a></li>
</ul>
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